Materials Science & Engineering Program, Texas A&M University, College Station, Texas 77843, USA.
Langmuir. 2011 Oct 4;27(19):12106-14. doi: 10.1021/la201584r. Epub 2011 Sep 7.
The influence of the clay deposition suspension concentration on gas barrier thin films of sodium montmorillonite (MMT) clay and branched polyethylenimine (PEI), created via layer-by-layer assembly, was investigated. Films grown with MMT suspension concentrations ranging from 0.05 to 2.0 wt % were analyzed for their growth as a function of deposited polymer-clay bilayers (BL) and their thickness, clay concentration, transparency, nanostructure, and oxygen barrier as a function of the suspension concentration. The film thickness doubles and the visible light transmission decreases less than 5% as a function of MMT concentration for 20-BL films. Atomic force and transmission electron microscope images reveal a highly aligned nanobrick wall structure, with quartz crystal microbalance measurements revealing a slight increase in the film clay concentration as the MMT suspension concentration increases. The oxygen transmission rate (OTR) through these 20-BL composites, deposited on a 179 μm poly(ethylene terephthalate) film, decreases exponentially as a function of the MMT clay concentration. A 24-BL film created with 2.0 wt % MMT has an OTR below the detection limit of commercial instrumentation (<0.005 cc/m(2)·day·atm). This study demonstrates an optimal clay suspension concentration to use when creating LbL barrier films, which minimizes deposition steps and the overall processing time.
研究了粘土沉积悬浮液浓度对通过层层组装形成的钠蒙脱石（MMT）粘土和支化聚乙烯亚胺（PEI）气体阻挡薄膜的影响。分析了悬浮液浓度范围为 0.05 至 2.0wt%的 MMT 悬浮液所形成的薄膜的生长情况，作为沉积的聚合物-粘土双层（BL）的函数以及它们的厚度、粘土浓度、透明度、纳米结构和氧气阻挡性能作为悬浮液浓度的函数。对于 20-BL 薄膜，薄膜厚度增加一倍，可见光透过率降低不到 5%，这与 MMT 浓度有关。原子力和透射电子显微镜图像显示出高度对齐的纳米砖壁结构，而石英晶体微天平测量结果表明，随着 MMT 悬浮液浓度的增加，薄膜中的粘土浓度略有增加。沉积在 179μm 厚的聚对苯二甲酸乙二醇酯薄膜上的这些 20-BL 复合材料的氧气传输率（OTR）随 MMT 粘土浓度呈指数下降。使用 2.0wt%的 MMT 制成的 24-BL 薄膜的 OTR 低于商业仪器的检测限（<0.005 cc/m2·day·atm）。本研究表明，在创建 LbL 阻挡薄膜时，使用最佳的粘土悬浮液浓度可以最小化沉积步骤和整体处理时间。
